The US National Park Service extends from the Badlands of South Dakota to Biscayne Bay, Florida. But did you know it used to cover more?

"Six percent of all the national parks that have ever been created have been dropped," Geographer Bob Janiskee told National Geographic. "During the sixties, seventies, and eighties, there was a period of tremendous growth, but it gets lost in the shuffle that parks also get abolished or decommissioned."

Some sites, like Mackinac National Park and the Lewis and Clark Cavern National Monument, were transferred from the national register to the care of their host states in cost-saving moves by the Feds. Others, like Mar-a-Lago National Historic Site or the National Visitor Center at Union Station in D.C. were either sold off to private interests or simply declared a wash.